As expected, the ambitious sci-fi "fever dream" John Carter tanked at the box office this weekend, earning just $30.6 million on its estimated $250 million budget and finishing behind the The Lorax (which is in its second week). By comparison, four recent films with similarly out-sized budgets — Spider-Man 3, Harry Potter and the Deathly Hallows, Avatar, and the most recent Pirates of the Caribbean sequel — averaged $99 million in their debut weekends. Observers had predicted that John Carter would flop, based on its poor performance in audience tracking studies. But now that the film has fulfilled those low expectations, they're enumerating the reasons. Here, six theories:

1. There was no star powerJohn Carter is a rarity: A massively-budgeted tent-pole film without a single recognizable name in its cast, says John Young at Entertainment Weekly. Producers cast a completely unproven lead, Friday Night Lights' Taylor Kitsch. And while Avatar starred a similarly untested Sam Worthington, "James Cameron's name is as big as any movie star," and Worthington was joined on screen by known-quantities like Sigourney Weaver and Michelle Rodriguez. "The most familiar face in John Carter was… Mark Strong?"

2. The marketing was a misfireThe movie is the victim of some "really rotten marketing," says Nikki Finke at Deadline. A series of bland, confusing trailers — "as generic" as the film's title — failed to convey the scope of the Civil War-to-Mars story or build interest around the characters. Though you wouldn't know it from the trailers, the film features a compelling love story, which could have snagged female audiences. Shortening the title from the original John Carter of Mars also turned the film into "a sphinx," says Young. "Who is John Carter? Where is he? Why can he leap great distances?" The marketing answered none of these questions.

3. The young guys didn't show upJohn Carter is the kind of effects-heavy, action-adventure sci-fi film that's supposed to appeal to the young male demographic that flocked to Transformers or Clash of the Titans, says Amy Kaufman at the Los Angeles Times. Yet the audience that turned out this weekend was surprisingly older; 59 percent were over age 25. Blame the marketing again, says Finke. The studio mistakenly catered to the fanboys of the source material instead of the general public. See exhibit A, says Young: The Super Bowl commercial that "wrongly assumed audiences were so familiar with the John Carter brand that simply seeing the movie's title would excite them."

4. The reviews didn't sell any ticketsCritics were largely polite to John Carter, says Robert Fure at Film School Rejects. Apart from a few hyperbolic raves and pans, most reviews fell into "it's alright" territory. "Consensus is you'll probably think the movie is okay, but you might want to wait for the DVD" — a death knell for a film that cost $250 million to make.

5. It never overcame the initial negative buzzThe movie was "doomed by its first trailer," says Claude Brodesser-Akner at New York. That first action-less and effects-less trailer in July was so "disastrously impotent [and] muddled" that audiences were simply left thinking, "What was that?" Later attempts to refine the marketing campaign came too late. The film "had become a punch line — to those on whom it managed to register at all." Once the "established simplistic narrative that the film is a big-budget flop started to take hold in the press," says Mark Hughes at Forbes, the negative buzz spread so quickly and so loudly that John Carter never stood a chance.

6. Nobody, it seems, wants to go to MarsDisney now has three relatively recent films set on Mars that have flopped. See previous box office duds Mission to Mars and Mars Needs Moms. "Avoiding the red planet for the next few decades might be a smart move for the Mouse House," says Gregory Ellwood at HitFix.